ATLANTA, Georgia (CNN) – A U.S. District Court judge has ruled that a school district in suburban Atlanta, Georgia, must remove an evolution disclaimer inside textbooks.

The stickers inside the Cobb County School District’s science books said “Evolution is a theory not a fact.”

The ruling issued by U.S. District Judge Clarence Cooper said the stickers violate the Establishment Clause of the U.S. Constitution.

Parents in Cobb County, a politically conservative area northwest of Atlanta, and the American Civil Liberties Union had challenged the stickers in court, arguing they violated the constitutional separation of church and state.